Abstract: A flat slot array antenna as composed of a waveguide having a rectangular sectional shape, and a power feeder means connected to the waveguide at a power feed opening. A plurality of wave radiation slots are formed within one of the metallic plates forming the waveguide. The length of each slot is progressively increased toward a terminal end of the power propagation within the space of the waveguide within a range which does not exceed the resonance length of the slot, and the distance between the slots is progressively reduced toward the terminal end of the waveguide.

Abstract: A pair of opposite metallic plates are disposed at an interval with respect to each other so as to form a wave guide space without side plates. A plurality of power radiating slots are formed within one of the metallic plates. A lens antenna is provided for forming a flat equiphase plane wave at the power feed opening of the wave guide space, so that the power is propagated within the wave guide space in the TE mode and radiated from the slots.

Abstract: A slot array antenna is composed of a rectangular waveguide formed by means of oppositely disposed plates and side plates, and a power feeder means connected to the rectangular waveguide at a power feed opening. A plurality of wave radiation slots are formed within one of the plates. The power feeder means is arranged such that two powers fed therein are changed into two plane waves, at the power feed opening, having two independent dominant modes. The slots comprise longitudinal slots extending in a longitudinal direction of the waveguide and lateral slots extending in a lateral direction of the waveguide so as to radiate two plates waves respectively.